DE2851504A1 - Dual type IC vehicle engine - has compression ignition at part load and spark ignition at full load - Google Patents

Abstract

The engine has a piston reciprocating in a cylinder with a swirl chamber in the cylinder head. There is a sparking plug in the swirl chamber and a fuel injector in the main cylinder. The accelerator operates both a throttle in the carburettor and a fuel injection pump. A relay energises coils which stop fuel flow in the carburettor open the throttle and bring the injection pump into operation. The coil of the relay is energised through a tachometer or through a switch on the accelerator or through an engine thermometer. Any one of these signals bring the spark ignition system into operation at full load.

Description

Method for operating an internal combustion engine and variable compression ratio, as well as internal combustion engine for performing the method

The invention relates to a method according to the preamble of Main claim. The invention also relates to an internal combustion engine for carrying out the method.

Known internal combustion engines stick to the Otto or diesel process certain disadvantages, particularly when these internal combustion engines are operated in motor vehicles over a wide load and speed range do not allow a satisfactory degree of efficiency. While the spark ignition internal combustion engine at higher speeds or in the full load range works satisfactorily, its efficiency in the partial load range is due to the control-related throttle losses and the associated lower compression end pressure relatively bad; If the internal combustion engine is operated very leanly, this also results in unstable operation due to misfiring.

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In contrast, the diesel internal combustion engine, which is known to work with Excess air is operated because of their high compression and auto-ignition in the partial load range at lower speeds with good efficiency and low pollutant emissions; However, this efficiency decreases with increasing speed of the internal combustion engine due to the ignition delay and the limited burning speed of the compressed charge - unsatisfactory in diesel internal combustion engines is also their cold running, the has the effect of nailing noises and a low initial output, especially when operating the diesel internal combustion engine in motor vehicles is disturbing.

The invention would provide a method and an internal combustion engine for performing the method with which a good efficiency and stable operating behavior can be achieved over a wide speed and load range. In addition, the method according to the invention should be relatively easy to carry out _o

The procedural task with the features of claim 1 solved. It is therefore proposed according to the invention that the ranges are satisfactory Efficiency of both internal combustion engines (Otto-Diesel) in to unite an internal combustion engine by starting from the diesel process in the partial load range with a defined Switching point reduces the compression and switches to the Otto process through external ignition. This eliminates the disadvantages described of the diesel process eliminated in the higher load or speed range. The change in compression advantageously takes place abruptly.

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In order to achieve an optimal combustion process in both operating phases of the internal combustion engine, the internal combustion engine can use diesel fuel in the partial load range and operated with petrol at full load. It however, there is also the possibility of suitably coordinating the internal combustion engine to operate these in both operating phases with only one type of fuel, for example with gasoline.

With the features of claim 3, disturbing noises can Internal combustion engine and unsatisfactory operating behavior during cold running can be avoided.

Claims 4 and 5 characterize two advantageous options of switching from compression ignition to positive ignition, especially in the case of a internal combustion engine operated according to the method in a motor vehicle A combination of both connectivity options should be advantageous, since in the case of a speed-dependent switchover, the economic aspects (fuel consumption) and in a load-dependent switchover the performance (e.g. when accelerating) can be taken into account ^ i; the two switching points can thus correspond to the requirements of each other differ-

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In the case of an internal combustion engine with several piston-cylinder units be proceeded according to claim 6 so that during the switching of least of Compression ignition to spark ignition some of the piston-cylinder units are operated with spark ignition and others with compression ignition. This will a stable operating behavior of the internal combustion engine in the transition states achieved.

An internal combustion engine according to the invention for carrying out the method can be found in the features of claim 7. A sudden change in the geometric compression ratio becomes easier Way achieved by the arrangement of a valve in the overflow channel.

Contribute to a reliable operating behavior of the internal combustion engine the features of claim 8, through which the internal combustion engine can be operated relatively lean in Otto operation, since the charge first is ignited in the secondary combustion chamber and the combustion process then spills over to the main combustion chamber by safely igniting the torch; In addition, it is ensured that the spark plug, since it is separated from the main combustion chamber, during the auto-ignition phases of the internal combustion engine not sooty. .

According to claim 9, an injection nozzle can be arranged in the main combustion chamber be. The fuel for diesel operation can be fed through this nozzle known direct injection processes are supplied; it exists also the possibility of using only one type of fuel for the

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Auto-ignition and spark-ignition operation the entire fuel supply operate via this injector.

However, according to claim 10, an injection nozzle can also be used in the secondary combustion chamber be arranged, via which Otto fuel is supplied during operation of the internal combustion engine with spark ignition.

Due to the features of claim 11, the internal combustion engine in compression ignition operation based on the principle of a pre-engine diesel internal combustion engine or a Wirbelkamirier diesel internal combustion engine which "internal combustion engines" get through a quieter combustion process distinguish.

In an internal combustion engine, in the one leading to the main combustion chamber Intake pipe of a mixture preparation system charged with petrol and a throttle valve cooperating with an accelerator pedal are arranged, the switch from compression ignition to spark ignition becomes more advantageous Way achieved by the features of claim 12. The mixture preparation system can be both a carburetor and one that injects into the intake manifold Be gasoline injection system.

By arranging a temperature sensor at a suitable location on the Internal combustion engine according to claim 13 can be achieved that the internal combustion engine during its cold state of auto-ignition operation is switched to spark ignition operation, so that in particular hard combustion noises (Nailing) should be avoided. Has the internal combustion engine

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reaches a defined temperature, it is determined by the temperature sensor switched to compression ignition mode or diesel mode. Overall, the invention creates an internal combustion engine that has the advantages of the Otto process combined with those of the Diesel process. If not high Power needed, for example in city traffic, can be economical be driven with compression ignition. When high performance is required can be driven with spark ignition.

An example of a method according to the invention and an internal combustion engine for performing the method are described in more detail below with reference to a schematic drawing.
'The drawing shows in

PIg. 1 shows a cross section through an internal combustion engine according to the invention with a main and a secondary combustion chamber and a device for switching from diesel to gasoline operation,

FIG _o 2 is a cross section through an inventive combustion engine with a main, a secondary combustion chamber and a pre-chamber.

Ih FIG _o 1, 1 denotes a reciprocating internal combustion engine having a cylinder housing 2, a piston 3 and a cylinder head. 4 The piston 3 can be moved up and down via a connecting rod 5 and a crankshaft 6 and delimits a main combustion chamber 7 with the cylinder head 4 and the cylinder housing 2.

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In the cylinder head 4, an exhaust duct with an outlet valve (not visible in the sectional plane shown) and an intake duct 8 with an inlet valve 9 are arranged in a known manner. An overflow duct 10, which is connected to a secondary combustion chamber 11, also opens into the main combustion chamber 7. The secondary combustion chamber 11 is designed, for example, in the manner of a vortex chamber known per se; d. h _o that the overflow channel 10 opens tangentially into the secondary combustion chamber 11. The secondary combustion chamber 11 can be cylindrical, in which case the overflow duct extends over the entire axial length of the secondary combustion chamber and, as a result of its relatively large cross section, brings about low flow losses. In the area of the overflow channel 10, a rotary roller valve 12 is inserted into the cylinder head 4, which has a transverse slot 13 corresponding to the cross section of the overflow channel 10 (see enlarged detail X in FIG. 1). The overflow channel 10 can thus be blocked by turning the rotary roller valve 12 by 90. Finally, a spark plug 26, which is supplied by a conventional ignition system (not shown), protrudes into the secondary combustion chamber.

An injection nozzle 14 protrudes into the main combustion chamber 7 via a line 15 is connected to an injection pump 16 and via the Injection method Diesel fuel can be injected into the main combustion chamber 7.

An intake pipe 17 and a carburetor 18 as a mixture preparation system are attached to the intake duct 8 connected for petrol or petrol. The carburetor 18 is essentially of a known type and therefore its function not described in detail. A control the intake cross-section in the carburetor 18-

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de throttle valve 19 is via a lever 20 and a cable 21 operated by an accelerator pedal 22. About another cable 23 and a two-armed lever 24, a control rod 25 for adjusting the delivery rate of the injection pump 16 is actuated.

For switching from compression ignition during operation of the internal combustion engine for spark ignition, a device is provided which essentially consists of a double contact relay 27, a speed-dependent relay Switch 28, a breaker switch 29 actuated with the accelerator pedal, an electromagnetic one that shuts off the fuel supply in the carburetor 18 Valve 30, an electromagnet 31 adjusting the throttle valve, an electromagnet 32 adjusting the control rod 25 of the injection pump 16 and finally from a rotary roller valve 12 rotating by 90 °, electromagnetic actuator 33 is made. The control winding 34 of the double contact relay 27 can be applied to the positive potential of a current source 36 via an ignition switch 35. On the other hand, the control winding 27 is over corresponding lines with the speed switch 28, the breaker switch 29 and a temperature sensor 37 and is connected when a defined speed of the internal combustion engine is exceeded, when the accelerator pedal is depressed placed over a certain distance or when falling below a lower temperature of the internal combustion engine to negative potential.

If the circuit of the control winding 34 is closed (illustrated arrangement), the contact bridge 38 of the double contact relay 27 connects the valve 30 to the positive potential of the power source 36 via corresponding lines, see above that the valve 30 opens and the internal combustion engine i in a known manner

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Fuel-air mixture is supplied. At the same time, about the too Electromagnet 32 lying at the positive potential, the control rod 25 of the injection pump 16 set to zero funding, that is also at the plus potential lying electromagnetic adjustment part 33 rotates the rotary roller valve in a position that opens the overflow channel 10, so that the main and Sub-burner spaces are connected to one another.

If the circuit of the control winding is interrupted 34, so does the contact bridge 38, a dashed line position, connecting the lever 20 of the throttle valve 19 actuates solenoid 31 with the positive potential, whereby this pulls the throttle valve 19 in a fully open position. At the same time, the valve 30, the electromagnet 32 and the electromagnetic control part 33 are de-energized, so that the valve 30 closes and interrupts the gasoline supply, the injection pump 16 is put back on promotion and the rotary slide valve is turned back into its position blocking the overflow channel 10

The geometric compression ratio of the internal combustion engine 1 is designed according to the method according to the invention so that when the overflow duct 10 is closed, a compression ratio of, for example, 22 and, when the overflow duct is open, a compression ratio of, for example, 10 is achieved by adding the secondary combustion chamber volume. In partial load operation, for example at engine speeds below 3000 min ", the internal combustion engine is operated with self-ignition, ie the overflow duct 10 is shut off and the main combustion chamber is opened by means of the injection pump 16 via the pipe 15 and the injection valve 14

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Diesel fuel supplied. The amount of fuel injected is controlled in a known manner by pressing the accelerator pedal 22 and adjusting the control rod 25 accordingly. Since the electromagnet 31 is at positive potential, the throttle valve 19 is fully open ₈ so that no major throttle losses occur in the intake path of the internal combustion engine and the internal combustion engine can be operated with excess air.

If the internal combustion engine exceeds the specified speed or is at As the load on the internal combustion engine increases, the accelerator pedal 22 is depressed so far that the breaker switch 29 closes, so the internal combustion engine is turned off switched to external ignition, or their geometric compression ratio by opening the overflow channel 10 suddenly changed from 22 to 10. At the same time, by attracting the electromagnet 32, the delivery of the injection pump 16 is stopped and the fuel supply through the valve 30 is opened. Since the circuit to the electromagnet 31 is interrupted, the throttle valve 19 can be removed from the accelerator pedal 22 in a known manner via the cable 21 being controlled. The fuel-air mixture is then different from that in the secondary combustion chamber 11 protruding spark plug 26 spark-ignited. According to the method, the internal combustion engine is thus in the higher speed range or in a higher load state operated with spark ignition at a reduced geometric compression ratio; regardless of this, it is used over the entire operating range External ignition operated when its temperature is below, for example, 60 C sir The connection takes place via the temperature sensor 37.

In the case of the internal combustion engine 40 shown in FIG. 2, on which only those from the internal combustion engine 1, the injection nozzle 14 protrudes continuously into a main combustion chamber 41 via an overflow channel 42 open prechamber 43. The internal combustion engine 40 is thus in the partial load range

operated according to the known pre-chamber diesel process in the lockable A further injection nozzle 44 projects into the secondary combustion chamber 11, by means of which gasoline can be injected into the secondary combustion chamber 11. With spark ignition can thus a stratification of the charge can be achieved in ^ that via the intake duct 8 either only air or a very lean fuel-air mixture is supplied is while in the sub-chamber 11 by direct injection of gasoline a reliably igniting fuel-air mixture is provided. The switchover the internal combustion engine can change from compression ignition to spark ignition in the same way as shown in FIG. 1.

In the case of multi-cylinder internal combustion engines, it can be advantageous if switching between at least two cylinder groups is delayed in time takes place, so that in load transition states one group of cylinders works with compression ignition and the other cylinder group already works with spark ignition. Such a switch is, for example, in an internal combustion engine with two carburetors and a specially designed injection pump, whose pump elements are controlled by a separate control rod for each cylinder group, easy to implement. Instead of a carburetor the use of a gasoline injection system with injectors protruding into the intake path is also conceivable »

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Claims (13)

AÜDlfitSU AUTO ra ^ ÖM :. j 1 ^^^, the Aktlengesellechaft * IP 1580 Za / L Process for operating an internal combustion engine with internal combustion and variable compression ratio, as well as internal combustion engine for carrying out the process. Expectations 1. Method for operating an internal combustion engine lind variable compression ratio at which a working volume is compressed and an air-fuel mixture contained in the compressed volume burns after ignition and expands while releasing energy, thereby characterized in that the geometric compression ratio in the partial load range the working volume is increased so that the air-fuel mixture ignites itself, and the internal combustion engine in the full load range wire operated with spark ignition at reduced compression ratio. 2. Vsrfahren according to claim 1, characterized in that that the internal combustion engine runs on diesel fuel in the partial load range and in the Full load range is operated with Otto fuel. -2- 030023/0362 3. The method according to claim 1 or 2, characterized gekennzeichm e t that the internal combustion engine is operated in the cold state with a reduced compression ratio only with spark ignition. 4. Internal combustion engine according to claims 1 to 3, characterized that the switching on from compression ignition to spark ignition takes place as a function of the speed of the internal combustion engine. 5. Process according to claims 1 to 4, characterized that the switching on from compression ignition to spark ignition takes place depending on the load condition of the internal combustion engine, 6. The method according to claims 1 to 5, wherein the internal combustion engine has several piston-cylinder units with working volumes formed therein, characterized in that in load transition states some of the piston-cylinder units are operated with spark ignition and others with compression ignition. 7. Internal combustion engine for carrying out the method according to one of claims 1 to 6, with a piston-cylinder unit in which a main combustion chamber is delimited by the piston, which is connected to a secondary combustion chamber via an overflow channel, characterized in that the overflow channel (10) a valve (rotary roller valve 12) is arranged so that the geometric compression ratio of the working volume is increased when the valve is closed. 8. Internal combustion engine according to claim 7, characterized in that a spark plug (26) is arranged in the secondary combustion chamber (11). 9o internal combustion engine according to claim 7 or 8, characterized that an injection nozzle (14) is arranged in the main combustion chamber (7) ο 10o internal combustion engine according to claims 7 to 9, characterized that an injection nozzle (44) is arranged in the secondary combustion chamber (11). 11. Internal combustion engine according to claims 7 to 10, characterized that with the main combustion chamber (41) a chamber (pre-chamber 43) is connected, in which an injection nozzle (14) for diesel fuel is arranged. 12 ο internal combustion engine according to claims 7 to 11, in which in a for Intake pipe leading to the main combustion chamber is a mixture preparation system charged with Otto fuel and a throttle valve cooperating with an accelerator pedal are arranged, characterized in that a device is provided with which the mixture preparation can be shut off and an injection pump (16) for injecting diesel fuel into the working volume can be put into operation » 13 “Internal combustion engine according to claims 7 to 12, characterized ,. da'ein temperature sensor (37) is provided, which is below a predetermined temperature of the internal combustion engine whose operation is set to external ignition. 030023/0362